Mary Han was a successful civil rights attorney who for decades battled over the rights of abused women, accused prostitutes and the homeless. In the close-knit Albuquerque legal community, she was known as a spitfire whose fervor was often directed at one entity in particular: The city’s troubled police department.

Now, more than two years after Han was found dead in her garage in what authorities deemed a suicide, the department is under scrutiny amid questions over whether officers mishandled the investigation into the death of their former adversary.

The state attorney general’s office is looking into the matter. It has also asked federal officials, who last year launched a civil rights probe into the department’s high number of police shootings, to look at the case.

Han’s relatives, meantime, have sued the city — along with the police chief, public safety director and more than a dozen officers and investigators — alleging shoddy police work resulted in a flawed investigation. More so, they question whether police failed to look at other explanations for the feisty and notoriously foul-mouthed attorney’s death.

“I would like to know what happened to my mother someday,” said Han’s 28-year-old daughter, Katherine, who remains steadfast in her belief that her mother did not kill herself. “To have an important person removed from their life without explanation is something no one should ever have to deal with. It’s more about peace of mind.”

Friends and fellow lawyers have also expressed doubt about suicide, noting that the 53-year-old Han was not one to give up on anything. But what really happened to Mary Han the night of Nov. 17, 2010, may forever remain a mystery.

Han’s law partner, Paul Kennedy, discovered her body the next morning in the garage of her home after she failed to come to work or contact her assistant.

She was sitting in the driver’s seat of her BMW, reading glasses on, feet propped up on the dash with the driver’s door and the windows open, according to police reports. Found in the car were a pair of brown slippers, a robe with a bottle of Ambien in the pocket and a glass with clear liquid. The door between the garage and the house was open.

The lawsuit brought by Han’s daughter and sister alleges a series of missteps that followed the discovery of her body, beginning with the seemingly extraordinary number of people who showed up to “trample” through the house and death scene. Police reports back claims that more than two dozen officers and city officials went to the house that day, and many saw Han’s body.

Specifically, the lawsuit alleges police violated standard procedure by almost immediately declaring the case a suicide and failing to lock down the home for processing as a potential crime scene. It also claims officers failed to properly preserve evidence, noting that two family heirloom diamond rings worth $100,000 that Han wore regularly were missing and never found.

An autopsy found the carbon monoxide level in Han’s blood to be 84.8 percent, and the medical examiner declared her death a suicide. However, the family’s lawsuit notes that Han’s car was outfitted with a device to shut it down before toxic amounts of carbon monoxide could be released, and that it was neither running nor had run out of gas when Han was found.

The lawsuit also contends the carbon monoxide level is “incredibly high” and, therefore, an “improbable cause of death” from ambient exposure.

In one police report, former Albuquerque officer Thomas Grover said he found it unusual that Han’s car door and windows were open. He noted that in previous car suicides he had investigated, the windows were rolled up and the vehicles secured.

“Something really bad happened, and APD made it worse,” said Grover, who was a close friend of Han’s and quit the department over her case. As one of the officers on scene that day, he is named in the family’s lawsuit, even though he agrees with its assessment that the department “really dropped the ball with so many things.”

The police department referred questions to the city attorney’s office. Assistant City Attorney Kathryn Levy said the investigation was complete and thorough. “Allegations … are just that. They must be proved, and the evidence will not support the allegations,” she said.

Levy said the police on scene were respectful and professional. Others noted that many of those who visited the scene were officials who had come to know Han over the years and considered her a friend, even if they were on the opposing side of her lawsuits.

Han was a prominent figure in the legal community, known for her aggressive nature and vulgar tongue. Over the years she made many friends and enemies on both sides of the law, acquaintances said.

The city and its police department were often targets in the cases she handled. She won a nearly $1 million civil judgment on behalf of a prostitute who said she was raped by a police officer. She also represented everyone from partygoers to elderly couples who claimed to be victims of excessive police force. But Han also defended officers who were wrongly accused.

“Mary Han had a fairly extensive history of representing people either very vulnerable to actions by the government or police department,” said Grover. “She was drawn to those plaintiffs or those defendants that were really sort of people that would fall victims to larger sources of power.”

A top official with New Mexico Attorney General Gary King said the office decided in January to look at the Han case. The official spoke on condition of anonymity, citing a policy against commenting on ongoing investigations. The official said the office also asked federal officials to look at the case as part of a civil rights probe of 28 police shootings that have killed 18 people over the past three years. The FBI and the U.S. attorney’s office declined to confirm or deny any investigation.

In a city increasingly leery of the integrity of its police department, given the federal probe and several high-profile excessive force cases, criticism of the agency has escalated in the wake of Han’s death. Jim Baca, a former Albuquerque mayor who pens an online blog called “Only in New Mexico,” wrote about the case last year after the Albuquerque Journal reported on how police handled the crime scene.

“When stories like this keep oozing out then you know there is a lot more packed inside the issue,” he wrote. “It certainly reveals the institutional problems at the department and that can only be fixed with a wholesale housecleaning.”

Conspiracy theories about how Han died also abound. Han’s family declined to speculate on what they think happened to her. But Grover said he believes Han was murdered, although he has no idea by whom. James Juliano, a private investigator working on behalf of the family, has his own theory: accident.

“It appears to me that she was in the vehicle working for whatever reason,” he said, noting the heat wasn’t working in at least part of her house. “Maybe she pulled in and decided to leave the car running, or got into the vehicle and was going to get work done and then was going to the gym.”

Juliano, a former field investigator for the city’s medical examiner’s office, said he found nothing to indicate foul play. But he also doesn’t believe Han fit the profile for suicide.

“There was nothing to indicate she was depressed. Her financial situation was fine. She was looking forward to holidays with the family.”

Still, he said, the myriad unanswered questions could have been eliminated if police had properly locked down and fully investigated the scene.

Said Juliano: “If things are not done right in the beginning, it creates a lot of conspiracy theories.”